Technical, Techniques, Hints, and Tips > The "Black Arts!" ( Electrics & Electronics )
P94 mixer
Paragon:
Hi all . Hope someone can help .
I am using a p94 action mixer for the first time.
I have it wired through a P92 power distribution board with two 540 brushed motors running on two 7.2 volt batteries wired in parallel.
I have it wired in fine and running well , mixing as it should.
The issue I am having is the steering servo seems to be doing a lot of twitching when I engage the throttle.
I have the receiver using its own power supply and I’m using a 2.4ghz Hitec optic set .
Anyone any idea?
Thanks
John
malcolmfrary:
Just how separate is the RX supply? The P92 has a BEC to supply the RX, and, through the RX, the servo and the input side of the P94.
Servos work by comparing the position that they think they are at with what their incoming instruction tells them it should be, and driving the motor to eliminate the difference. The reference is derived from the supply voltage of the servo. If that fluctuates due to changing load, the servo tries to keep pace, often changing the load. The radio could also have it reference voltage messed up by changing supply voltage.
The P92 and P94, between them, should have a good solid ground line connection, with power only going via the heavy wiring, but that is worth re-checking.
Less likely with modern radios is motor generated interference, but a frequent offender on AM systems. This usually had the most effect on Channel 1, almost invariably the rudder channel.
roycv:
Hi Malcolm I recently bought some (cheap) 9 grm servos and they all chattered in use on 27 and 40 Mhz. I wondered if as electric motors do not apparently interfere with 2.4ghz equipment there is not the same noise reduction capacitors on the servo motors that are currently on sale. There are implications for using replacement servos on old equipment.
Any ideas?
regards Roy
Colin Bishop:
From comments made in the past by Dave Milbourn it may be a signal timing issue. The current R/C sets have a different rate to the older ones and some servos might not be able to accommodate this.
Colin
Paragon:
Thanks for the replies
Malcolm The Rx is using its own power supply as suggested in the instructions for the P94 . No power coming from either the p92 or p94 . Both motors are suppressed but I don’t think this should matter running 2.4ghz system . The twitching hasn’t got great travel just quite quick and erratic but does only happen when the throttle is engaged.
Roy I am running 2.4ghz system the motors should not be causing the issue . As I have gather from various other threads .
Colin do you suggest trying a different possibly an older servo ?
Thanks
John
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